Refrigerating apparatus



April 10, 1934. N. J. SMITH 1,954,498

REFRIGERATING APPARATUS Filed July so. 1951 H l5 ATTORNEYS.

vf M ww z 2 7 Y i f x W W mmf f /A v X4. m l n wmllmwl u m 7 m e l 3 a hwy! M IKW/l m@ l i. i. i. M H v Patented Apr. 10, 1934 PATENT OFFICE 1,954,498 REFRIGERATING APPARATUS Nelson J. Smith, Dayton, Ohio, assignor to Frigidaire Corporation, Dayton, Ohio, a corporation of Delaware Application July 30, 1931, Serial No. 554,038

This invention relates to refrigerating systems and particularly to means for insuring starting f the circulating element employed to circulate the refrigerant through the system. p

Heretofore, in refrigerating systems wherein a refrigerant which is miscible with a lubricant, contained in the refrigerant circulating element to lubricate operating parts thereof, it has been found that evaporated or gaseous refrigerant entering the circulating element from the evaporator of the system Will be readily absorbed or mixed with the lubricant contained in thefcirculating element. When this occurs, the level of the body of lubricant in the circulating element increases abnormally and upon starting of the circulating element, this mixture of lubricant and refrigerant will be drawn into the cylinder of the circulating element. Since the circulating element must be designed to eiciently pump 20 gaseous refrigerant, the valve employed in the element to separate the system into a high pres- Claims.

sure portion and a low pressure portion, will not Y permit allrthe liquid mixture of refrigerant and lubricant to pass therethrough before the piston of the element reaches the end of its compression stroke. `This results inV the piston of the circulating element being forced against a trapped `body of liquid in the cylinderthereof which tends to stop the travel of the piston and consequently puts an abnormal load on the driving means for the circulating element causing it'to stall. At the beginning of operation of the compressor, the compressor driving means is ordinarily under .a relatively abnormal load in endeavoring to attain momentum and if an increased load is placed thereon during starting thereof, the driving means cannot get into motion. Such stalling of the driving means, if an electric motor, causes fuses in the electric power line leading thereto 4o to blow. Generally, refrigerating systems of this type are cyclically operated and therefore the heretofore mentioned stalling may occur each time the refrigerant circulating element is started unless some means is provided to prevent the p' liquid mixture from entering theV cylinder of the circulating element.

An object of this invention is to provide a cyclically operated refrigerating system of the type employing a refrigerant miscible o1' partially miscible with lubricant in which there is no danger of stalling or.breaking the driving means for the refrigerant circulating element.

Another object of the invention is to provide a definite predetermined level of lubricant in a refrigerant circulating element of a cyclically operated refrigerating system when operation of the element begins.

Another object of the invention is to remove and maintain a quantity of lubricant from the main -body thereof in the refrigerant circulating element to prevent a detrimental elevation of level in said main body, and to return this removed quantity of lubricant directly to the main body thereof in the circulating element after the element has operated for a short period of time.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 discloses a refrigerating system shown `diagrammatically having my invention embodied in the refrigerant circulating element thereof which is shown on an enlarged scale partly in vsection and partly in elevation.

Referring indetail to the drawing, I have shown for the purpose of illustrating my invention a compressor-condenser-expander type of refrigerating system employing an expansion valve for admitting refrigerant to the evaporator of the system and a thermostat responsive to temperatures of the evaporator for actuating a switch for starting and stopping operation of the system. ble to a so-called iiooded refrigerating system in which a float valve controls the entrance of refrigerant to the evaporator and in which operation of the system is controlled by a switch responsive to pressures in the system. My invention may be of more importance when applied to the latter type of a refrigerating system due to the relatively large quantity of refrigerant in such system which must be circulated in absorbing contact with the lubricant containedtherein.` The system disclosed in the drawing comprises a refrigerant circulating element or compressor l0 operated by an electric motor l1. The compressor forces refrigerant such as diiiuorodichloromethane (CCl2F2) or any other suitable refrigerant through the check valve l2 and through conduit or pipe 13 into a condenser 14. 'I'he compressed refrigerant is condensed and liquefied in condenser 14 and collects in receiver 16. From the receiver 16 the liquefied refrigerant passes by pipe 17 through an expansion valve 18 and into the cooling coils or evaporator 19 of a refrigerating element where it performs its refrigerating effect in the well-known manner. From the cooling coil 19 the vaporized refrigerant However, my invention is equally applicapasses by means of the pipe 21 back to the refrigerant circulating element or compressor 10. The thermostatic device is represented by 22 and is disposed so as to be responsive to the temperatures of the cooling coil 19 or may be responsive to the space being refrigerated by this coil. This device is used to actuate as by means of a diaphragm, bellows or the like 23, a circuit-making and breaking switch 24. This switch is shown in its motor non-operating position by the full lines and contacts 25 and 26 and in its operative position by the dotted lines.

After the system is put in operation and the compressor 10 has been idle for a short period of time, pressure within the evaporator 19, pipe 2l, and the compressor crank case 28 is relatively high. During this idle period, the temperature of fluid in bulb 22 rises and increases its own vapor-pressure, and this pressure acting in the flexible diaphragm or bellows 23 will expand same and thus force the switch 24 and its contacts 25 and 26 into circuit-making position to cause operation of the motor 1l employed foi driving the refrigerant circulating element or compressor 10. After the compressor has operated for a short period, say for a few minutes the temperature of the environment of bulb 22 is reduced, and the fluid pressure therein is reduced sufficiently to permit the diaphragm or bellows 23 to be contracted, thus actuating the switch contacts 25 and 26 into open position for breaking the electric circuit to the motor l1. Operations of the system continue as described as long as the system is connected with the source of power.

The compresser 10 may be of any suitable form and may include an eccentric 31 within the crankcase 28 which eccentric is secured to the rotating shaft 32 and has a connecting rod 33 actuated thereby. Movement of the connecting rod 33 reciprocates a piston 34 secured to the upper end thereof. This piston 34 has located therein the check valve 35 which opens upon the down stroke of the piston to permit the entrance of refrigerant gas into the cylinder 36 above the piston but seats or remains closed during the up or compression stroke thereof. A body of lubricant, indicated at 38, is adapted to be maintained within the crankcase 28 of compressor 10 for lubricating operating parts of the compressor.

The crankcase 28 of the compressor is on the low side of the system. While the compressor is operating, the refrigerant pressure therein is relatively low, but during the idle period this pressure gradually rises because of the rise of temperature of the liquid refrigerant in the low side. During this idle period, therefore, the refrigerant absorbing power of the lubricant in the crankcase increases and a quantity of refrigerant is absorbed, depending, of course, on the natural affinity between the two fluids, the ternperatuie of the lubricant and the pressures of the fluids. The volume of the lubricant (which is a mixture of oil and refrigerant with a major portion of oil) therefore tends to'increase due to this absorption of refrigerant during the idle periods. This is particularly true where the refrigerant and lubricant are miscible in all proportions, but the same problem exists, in varying degrees, even when they are only partially miscible.

In an apparatus not provided with my invention, the lubricant level, which should normally be at 49 for satisfactory operation, would tend to rise to a detrimentally high level, such as'41, during the idle period of the system. This rise in the level would occur because of the absorption of the refrigerant by the lubricant as described above. With such a detrimentally high oil level, a violent boiling or foaming would occur when the compressor starts due to the release of gaseous refrigerant from the lubricant by the quick reduction in pressure. Under such conditions, large quantities of liquid are likely to pass through the valve 35 into the compression chamber 36 with undesirable results readily apparent to those skilled in the art.

According to my invention, however, means are provided for preventing any such detrimental rise in lubricant level during the idle periods of the apparatus. To this end, an overflow trap 46 is provided which is conveniently made by attaching a bottom plate 44 with bolts 45 to the casing, and providing the overflow pipe or conduit 47 with its upper end at the level 49 and with its lower end terminating near the bottom of the trap 46. In addition, if desired, a relatively small breather passage or conduit 48 is provided between the trap 46 and the crank case 28 and it may conveniently be placed in the bearing portion 42 of the crankcase wall.

During the idle period of the apparatus when the lubricant is absorbing the refrigerant, the lubricant with the absorbed refrigerant overflows through the pipe 47 into the trap 46. Since this absorbing action is relatively slow, the breather 105 pipe 48 is of suflicient size to permit the pressures within the crankcase 28 and the trap 46 to equalize and permit a gravitational flow of the liquid from the crank case 28 to the trap 46. This overow action maintains the lubricant level at 49 notwithstanding the increase of volume of the lubricating mixture.Y When the compressor starts, because of its volumetric capacity, it quickly reduces the pressure in the crankcase 28 before the breather conduit 48 can equalize the pressure between the trap 46 and the crankcase 28. The result is that the pressure in the trap 46 is momentarily greater than in the crankcase 28 and thus forces liquid up through the pipe 47V into the crankcase 28 at a rate sufficient to maintain the liquid substantially at 49 or only slightly higher. The level does not rise much above 49 even Vwhen liquid is flowing up through the pipe 47 because a certain amount of refrigerant is boiling out of the body 38 due to the drop in pres- 125 sure and the consequent decrease in absorbing power of the oil. By the time that the breather pipe 48 equalizes the pressure between the crankcase 28 and the trap 46, a sufficient amount of liquid has been forced up through the pipe 47 130 to insure a sufficient amount of lubricant in the crankcase 28 for the normal operation of the compressor. When the compressor again stops and the absorbing action once again starts, the overow of lubricant mixture into the trap 46 is 135 repeated.

The trap 46 should be of suflicient capacity to hold all of the excess mixture of oil and refrigerant which is likely to overflow therein. The size of the passage or conduit 48 should be suffi- 140 cient to permit pressures to equalize only very slowly. As above pointed, it should permit the pressures to equalize while the oil is absorbing refrigerant during the idle period; but it should not be suicient to permit pressure equalization 145 during the starting moments of the compressor when it is desiredA to force liquid up through the pipe 47 to replace the refrigerant and slight traces of lubricant, which are removed from the lubri- Vcant body 38 during the starting'perio'd.

The slight amounts of lubricant which are carried through the compressor during the running period eventually nd their way back to the compressor after passing through the condenser and evaporator. These slight amounts of lubricant return to the crankcase 28. Therefore during the running period of the compressor, the level of the main body 38 tends to remain constant after the liquid has been forced up from trap 46 at the starting period and after the pressures have equalized between the trap 46 and crankcase 28.

Thus it is apparent that I have provided an improved refrigerating system which will not be rendered inoperative by the absorption of a quantity of the refrigerant in the lubricant. Furthermore, I have provided a system in which the lubricant and refrigerant employed therein are miscible or partially miscible and in which a detrimentally high lubricant level is prevented in the refrigerant circulating element during idle periods thereof while at the same time insuring proper lubrication of the operating parts of the circulating element during the major portion of the operating period thereof.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming Within the scope of the claims which follow.

What is claimed is as follows:

1. A refrigerating system employing a refrigerant and a lubricant in Which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, means for conducting a quantity of lubricant from the main body thereof in said circulating means, and means for maintaining said quantity of lubricant substantially out of absorbing contact with refrigerant in the refrigerating system during the off phase of each cycle of operation of the system and for causing the return of said quantity of lubricant directly to the main body thereof in the circulating means during the on phase of each cycle of operation of the system.

2. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant inthe crankcase of the compressor, means for conducting a quantity of lubricant from the main body thereof in said crankcase, and means for maintaining said quantity of lubricant substantially out of absorbing contact with refrigerant in said compressor during the off phase of each cycle of operation of the system and for causing the return of said quantity of lubricant directly to the main body thereof in the compressor crankcase during the on phase of each cycle of operation of the system.

3. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, a trap for receiving a quantity of lubricant from the main body thereof in the circulating means and for maintaining said quantity of lubricant substantially out of contact with refrigerant in said circulating means during the off phase of each cycle of operation of the system, and a conduit establishing communication between said circulating means and said trap for conveying said quantity of lubricant from thetrap directly to the circulating means during the on phase of each cycle of operation of the system.

4. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, a trap for receiving a quantity of lubricant from the main body thereof in the circulating means and for maintaining said quantity of lubricant substantially out of contact with refrigerant in said circulating means during the off phase of each cycle of operation of the system, and a conduit establishing communication between said circulating means and said trap for conveying said quantity of lubricant from the trap directly to the circulating means during the on phase of each cycle of operation of the system, said trap having a rectricted outlet for the escape of gaseous refrigerant therefrom during the entrance thereinto of said quantity of lubricant from said circulating means through said conduit.

5. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant in the crankcase of the compressor, a trap for receiving a quantity of lubricant from the main body thereof in the compressor crankcase and for maintaining said quantity of lubricant substantially out of absorbing contact with refrigerant in said compressor during the off phase of each cycle of operation of the system, and a conduit establishing communication between said compressor crankcase and said trap for conveying said quantity of lubricant from the trap directly to the compressor crankcase during the on phase of each cycle of operation of the system.

6. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant in the crankcase of the compressor, a trap for receiving a quantity of lubricant from the main body thereof in the compressor crankcase and for maintaining said quantity of lubricant substantially out of absorbing contact with refrigerant in said compressor during the olf phase of each cycle of operation of the system, and a conduit establishing communication between said compressor crankcase and said trap for conveying said quantity of lubricant from the trap directly to the compressor crankcase during the on phase of each cycle of operation of the system, said trap having a restricted outlet for the escape of gaseous refrigerant therefrom during the entrance thereinto of said quantity of lubricant from said compressor crankcase through said conduit.

7. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, means for conducting said lubricant from said circulating means, and means for maintaining said lubricant substantially out of absorbing contact with refrigerant in the refrigerating system during the off phase of each cycle of operation of the system and for causing the return of said lubricant directly to the circulating means for the on phase of each cycle of operation of the system.

8. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant in the crankcase of the compressor, means for conducting said lubricant from said crankcase, and means for maintaining said lubri cant substantially out of absorbing contact with refrigerant in said compressor during the ofl phase of each cycle of operation of the system and for causing the return of said lubricant di rectly to the compressor crankcase for the on phase of each cycle of operation of the system.

9. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circu lating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, a trap for receiving said lubricant from the circulating means and for maintaining said lubricant substantially out of contact with refrigerant in said circulating means during the off phase of each cycle of operation of the system, and a conduit establishing communication between said circulating means and said trap for conveying said lubricant from the trap directly to the circulating means for the on phase of each cycle of operation of the system.

10. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, means for starting and stopping said circulating means, a body of lubricant in said circulating means, a trap for receiving said lubricant from the circulating means and for maintaining said lubricant substantially out of contact with refrigerant in said circulating means during the off phase of each cycle of operation of the system, and a conduit establishing communication between said circulating means and said trap for conveying said lubricant from the trap directly to the circulating means for the on phase of each cycle of operation of the system, said trap having a restricted outlet for the escape of gaseous refrigerant therefrom during the entrance thereinto of said lubricant from said circulating means through said conduit.

11. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant in the crankcase of the compressor, a trap for receiving said lubricant from the compressor crankcase and for maintaining said lubricant substantially out of absorbing contact with refrigerant in said compressor during the off phase of each cycle of operation of the systern,and a conduit establishing communication between said compressor crankcase and said trap for conveying said lubricant from the trap directly to the compressor crankcase for the on phase of each cycle of operation of the system.

12. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system including a compressor having a crankcase, means for starting and stopping said compressor, a body of lubricant in the crankcase of the compressor, a trap for receiving said lubricant from the compressor crankcase and for maintaining said lubricant substantially out of absorbing contact with refrigerant in said compressor during the off phase of each cycle of operation of the system, and a conduit establishing communication between said compressor crankcase and said trap for conveying said lubricant from the trap directly to the compressor crankcase for the on phase of each cycle of operation of the system, said trap having a restricted outlet for the escape of gaseous refrigerant therefrom during the entrance thereinto of said lubricant from said compressor crankcase through said conduit.

13. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, a body of lubricant in said circulating means, means for conducting said lubricant from said circulating means, and means for maintaining said lubricant substantially out of absorbing contact with refrigerant in the refrigerating system when said means for circulating the refrigerant is not operating.

14. A refrigerating system employing a refrigerant and a lubricant in which the refrigerant is miscible with the lubricant, means for circulating the refrigerant through the system, a body of lubricant in said circulating means, a trap for receiving said lubricant from the circulating means and for maintaining said lubricant substantially out of contact with refrigerant in said circulating means when said circulating means is not operating, and a conduit establishing cornmunication between said circulating means and said trap for conveying said lubricant from the trap directly to the circulating means when said circulating means is operating.

NELSON J. SMITH. 

